Having watched several UFO conspiracy videos on youtube, I am really intrigued to dig deeper to find out what is going on.
Main points:
Germans created UFOs aroung the time of the second world war. Aliens live in underground bases (mainly in USA) Advanced technology is being exchanged with Aliens. People making these claims have worked in these areas, underground bases and are being killed off after making these claims.
Another Conspiracy:
The famous moon landing was fake and filmed by Stanley Kubrick, all the crew who worked on the filming have been killed off.
Yet another:
Water can be converted and used as a free energy source, again someone who claimed to have done this succesfully was killed off.